|Publication number||US7996533 B2|
|Application number||US 12/567,747|
|Publication date||9 Aug 2011|
|Priority date||17 Apr 2000|
|Also published as||US6996616, US7293093, US7596619, US8307088, US8806008, US20060168088, US20080065745, US20100011107, US20110307584, US20130246612|
|Publication number||12567747, 567747, US 7996533 B2, US 7996533B2, US-B2-7996533, US7996533 B2, US7996533B2|
|Inventors||F. Thomson Leighton, Daniel M. Lewin|
|Original Assignee||Akamai Technologies, Inc.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (22), Non-Patent Citations (6), Referenced by (48), Classifications (27), Legal Events (2)|
|External Links: USPTO, USPTO Assignment, Espacenet|
This application is a continuation of Ser. No. 11/934,894, filed Nov. 5, 2007, now U.S. Pat. No. 7,596,619, which application was a continuation of Ser. No. 11/347,988, filed Feb. 6, 2006, now U.S. Pat. No. 7,293,093, which application was a continuation of Ser. No. 09/836,735 filed Apr. 17, 2001, now U.S. Pat. No. 6,996,616, which application was based on and claimed priority from application Ser. No. 60/197,582, filed Apr. 17, 2000.
1. Technical Field
The present invention relates generally to high-performance, fault-tolerant HTTP, streaming media and applications delivery in a content delivery network (CDN).
2. Description of the Related Art
It is well-known to deliver HTTP and streaming media using a content delivery network (CDN). A CDN is a network of geographically distributed content delivery nodes that are arranged for efficient delivery of digital content (e.g., Web content, streaming media and applications) on behalf of third party content providers. A request from a requesting end user for given content is directed to a “best” replica, where “best” usually means that the item is served to the client quickly compared to the time it would take to fetch it from the content provider origin server. An entity that provides a CDN is sometimes referred to as a content delivery network service provider or CDNSP.
Typically, a CDN is implemented as a combination of a content delivery infrastructure, a request-routing mechanism, and a distribution infrastructure. The content delivery infrastructure usually comprises a set of “surrogate” origin servers that are located at strategic locations (e.g., Internet Points of Presence, access points, and the like) for delivering copies of content to requesting end users. The request-routing mechanism allocates servers in the content delivery infrastructure to requesting clients in a way that, for web content delivery, minimizes a given client's response time and, for streaming media delivery, provides for the highest quality. The distribution infrastructure consists of on-demand or push-based mechanisms that move content from the origin server to the surrogates. An effective CDN serves frequently-accessed content from a surrogate that is optimal for a given requesting client. In a typical CDN, a single service provider operates the request-routers, the surrogates, and the content distributors. In addition, that service provider establishes business relationships with content publishers and acts on behalf of their origin server sites to provide a distributed delivery system. A well-known commercial CDN service that provides web content and media streaming is provided by Akamai Technologies, Inc. of Cambridge, Mass.
CDNSPs may use content modification to tag content provider content for delivery. Content modification enables a content provider to take direct control over request-routing without the need for specific switching devices or directory services between the requesting clients and the origin server. Typically, content objects are made up of a basic structure that includes references to additional, embedded content objects. Most web pages, for example, consist of an HTML document that contains plain text together with some embedded objects, such as .gif or .jpg images. The embedded objects are referenced using embedded HTML directives, e.g., Uniform Resource Identifiers (URIs). A similar scheme is used for some types of streaming content that may be embedded within an SMIL document. Embedded HTML or SMIL directives tell the client to fetch embedded objects from the origin server. Using a CDN content modification scheme, a content provider can modify references to embedded objects so that the client is told to fetch an embedded object from the best surrogate (instead of from the origin server).
In operation, when a client makes a request for an object that is being served from the CDN, an optimal or “best” edge-based content server is identified. The client browser then makes a request for the content from that server. When the requested object is not available from the identified server, the object may be retrieved from another CDN content server or, failing that, from the origin server. This type of scheme is described in U.S. Pat. No. 6,108,703.
The above-described content delivery network and service provides significant advantages, namely, faster downloads for end-users, reduced load on the home site, flash crowd protection, easier web site management and infrastructure scaling, and the ability to distribute media-rich objects effectively.
It would be desirable to support the delivery of cacheable HTML from a content delivery network such as described above. The present invention provides this functionality.
A content delivery network is enhanced to provide for delivery of cacheable markup language content files such as HTML. To support HTML delivery, the content provider provides the CDNSP with an association of the content provider's domain name (e.g., www.customer.com) to an origin server domain name (e.g., html.customer.com) at which one or more default HTML files are published and hosted. The CDNSP provides its customer with a CDNSP-specific domain name. The content provider, or an entity on its behalf, then implements DNS entry aliasing (e.g., a CNAME of the host to the CDNSP-specific domain) so that domain name requests for the host cue the CDN DNS request routing mechanism. This mechanism then identifies a best content server to respond to a request directed to the customer's domain. The CDN content server returns a default HTML file if such file is cached; otherwise, the CDN content server directs a request for the file to the origin server to retrieve the file, after which the file is cached on the CDN content server for subsequent use in servicing other requests. The content provider is also provided with log files of CDNSP-delivered HTML.
The foregoing has outlined some of the pertinent features and advantages of the present invention. A more complete understanding of the invention is provided in the following Detailed Description of the Preferred Embodiment.
High-performance content delivery is provided by directing requests for web objects (e.g., graphics, images, streaming media, HTML and the like) to the content delivery network. In one known technique, known as Akamai FreeFlow content delivery, HTTP and/or streaming media content may be first tagged for delivery by the tool 106, which, for example, may be executed by a content provider at the content provider's web site 115. The initiator tool 106 converts URLs that refer to streaming content to modified resource locators, called ARLs for convenience, so that requests for such media are served preferentially from the CDN instead of the origin server. When an Internet user visit's a CDN customer's site (e.g., origin server 115) and, for example, selects a link to view or hear streaming media, the user's system resolves the domain in the ARL to an IP address. In particular, because the content has been tagged for delivery by the CDN, the URL modification, transparent to the user, cues a dynamic Domain Name Service (dDNS) to query a CDN name server (or hierarchy of name servers) 104 to identify the appropriate media server from which to obtain the stream. A CDN name server is sometimes referred to herein as a surrogate origin server, as it acts authoritatively on behalf of the CP origin servers who contract with the CDNSP. The CDN typically implements a request-routing mechanism (e.g., under the control of maps generated from the monitoring agents 109 and map maker 107) to identify an optimal server for each user at a given moment in time. Further details of a preferred dDNS-based request-routing mechanism are described below.
Metadata is data about the content provider's objects. More specifically, metadata is the set of all control options and parameters that determine how a CDN content server will handle a request for an object. To be handled by a CDN server, preferably all objects have a set of metadata associated with them, such as one or more of the following:
CP Code—an internal tracking number, primarily used for billing;
Serial Number—a CDN-specific value used for load balancing and monitoring;
Origin Server—the location of the original copy of the object, which a CDN server may need to fetch or revalidate the object;
Coherence information—information (e.g., fingerprint, time-to-live (TTL)) about how CDN servers should cache the object and maintain its freshness.
If a content provider uses CP-side content migration, e.g., through an initiator tool, the content provider's URI's are converted into alternate resource locators (ARLs) in the HTML. The ARL's contain all of the required metadata “in-URL” or, as sometimes referred to herein, “in-ARL.”
According to the present invention, the above-described content delivery network is enhanced to facilitate delivery of cacheable HTML from the edge-of-network servers. Once the HTML is cached at the CDN content servers, it is available for delivery to requesting end users. That HTML may include URLs that have been modified to point to the CDN as described above, but this is not a requirement of the present invention. URLs also may be modified to point to the CDN “on-the-fly,” namely, as the HTML is being served to the requesting end user.
For illustrative purposes, it is assumed that the content provider customer configures a default markup language file (e.g., index.html) to retrieve when an end user enters just a hostname (e.g., www.customer.com) in his or her browser. According to the invention, the CDNSP needs to associate requests for www.customer.com with the default HTML file www.customer.com/index.html. Thus, to integrate a content provider site for HTML delivery, the CDNSP must be provided with certain information from the content provider, namely, the domain name of the content provider's origin server. As noted, this identification is needed because, once provisioned, the CDNSP will begin receiving HTTP requests for the content provider's domain name (e.g., www.customer.com) and will need to know where to fetch the content provider's HTML when loading its content servers. In the example illustrated below in
Preferably, the content delivery network includes a logging and reporting mechanism to provide the content provider with real-time and historical information about the content served. According to the present invention, preferably the content provider is also provided information about the HTML served from the edge servers. In a preferred embodiment, the CDN has the ability to keep a single log file of the content provider's HTML hits in approximate real-time. The mechanism preferably provides content providers with real-time statistics, segmented by geo-location, of HTML traffic on the network, which may include, e.g., real-time counts of page views, visitors/unique users, and the like. Historical reporting of such information may also be provided. Log delivery also may include information such as cookie data, referrer data, user agent data, content-type data, and the like.
As described above, the content provider publishes an authoritative copy of the HTML as a default file. In the example above, the copy was index.html. To facilitate delivery, the content provider and/or the CDNSP must also publish “metadata” to the CDN content servers that enable the servers to associate a given host (e.g. www.customer.com) with particular content metadata that determines how the server will handle a request for the object. As a result, when the CDN content server receives a GET request, for example, it examines the host information in the host header against a host rewrite rule (e.g., provided by the content provider) to identify the given metadata that is to be associated with the content. A metadata transmission system may be used to securely publish metadata out to the edge servers for the host rewrite rules. Further details of such techniques are described in U.S. Pat. No. 7,240,100, titled “Content Delivery Network (CDN) Content Server Request Mechanism With Metadata Framework Support,” which is assigned to the assignee of this application.
The above-described technique facilitates the delivery of HTML and embedded content from the content delivery network. In summary, to support HTML delivery on the CDN, the content provider provides the CDNSP with the association of the content provider's domain name (www customer.com) to the origin server domain name that hosts one or more default HTML files. The CDNSP provides its customer with a CDNSP-specific domain name. The content provider, or an entity on its behalf, then implements DNS entry aliasing (e.g., CNAME the host to the CDNSP-specific domain) so that requests for the host cue the CDN DNS request routing mechanism. The content provider is also provided with access to log files of CDNSP-delivered HTML.
In an alternate embodiment, HTML may be delivered from the origin server to the edge server initially, or from the edge server to the requesting browser, in a compressed format. HTML transport compression reduces bandwidth requirements.
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|U.S. Classification||709/226, 718/105, 709/235, 707/999.01, 709/219|
|International Classification||G06F7/00, G06F9/46, G06F15/173|
|Cooperative Classification||H04L29/12009, H04L43/04, H04L61/15, H04L29/12047, H04L67/02, H04L67/1002, H04L67/28, H04L67/2842, H04L67/1021, H04L67/1008|
|European Classification||H04L29/08N27, H04L29/08N1, H04L29/08N27S, H04L29/08N9A, H04L61/15, H04L29/12A2, H04L29/08N9A1B, H04L29/08N9A1H, H04L29/12A|
|26 Sep 2009||AS||Assignment|
Owner name: AKAMAI TECHNOLOGIES, INC., MASSACHUSETTS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:LEWIN, ANNE E.;REEL/FRAME:023287/0899
Effective date: 20070112
Owner name: AKAMAI TECHNOLOGIES, INC., MASSACHUSETTS
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:LEIGHTON, F. THOMSON;REEL/FRAME:023287/0891
Effective date: 20050727
|21 Jan 2015||FPAY||Fee payment|
Year of fee payment: 4